Probably the number one way to make money online is the ability to create and sell your product. Not only are you in full control of the product, but you also get to keep how ever much profit per product you decide.
Too many times, people create products, sell them, and then forget about them. Unless your product has some sort of expiration date when it just won’t be useful anymore, then why not clean off the cobwebs and market it again?
By updating your products, yourself are also giving you another chance to remind or inform people about your products. At the same time, you are improving the value of your current customers, so they will be more likely to buy any of your future products.